The present invention relates to a system for providing fluid having a variable concentration of hydrocarbon therein for the purpose of depressing the freezing point thereof, with the fluid being supplied to the exterior surface of the vehicle such as a windshield, for the purpose of cleaning same.
Windshield washer systems have been used in automotive vehicles for many years. As is well known, such systems typically apply a fluid which aids the action of the wiper blades in cleaning the windshield or other exterior surface, such as a lamp lens. Because many vehicles are required to operate in ambient temperatures below freezing, it has been necessary to provide an additive to the fluid so as to depress its freezing point. Typically, methanol is used for the purpose of depressing the freezing point of the windshield washer fluid. However, as vehicle emission regulations become increasingly more stringent, it has become more desirable to limit the emissions of all forms of hydrocarbons from the vehicle. Accordingly, it is desirable to limit or reduce the use of methanol. Because it is difficult to use neat water at temperatures below freezing, the present system allows the blending of two liquids consisting of a windshield washer fluid having a reduced alcohol or other hydrocarbon content and a fluid comprising mostly freezing point depressant or additive. Unlike prior art systems which apply full strength windshield washer fluid whenever fluid is called for, the present system will provide fluid having only a minimal amount of alcohol required to present freezing. In this manner, the use of alcohol is reduced.
Herein, the term xe2x80x9chydrocarbon additivexe2x80x9d means any of the commonly used freezing point depressants employed with windshield washer fluid. Sometimes these fluids may include methanol, ethanol, or isopropanol. Those skilled in the art will appreciate in view of this disclosure, moreover, that other fluids based on hydrocarbons or other chemicals could be used with a system according to the present invention.
A windshield washer system for an automotive vehicle includes a washer fluid reservoir, fluid contained within the reservoir, with the washer fluid having an aqueous base and a hydrocarbon additive and a separator for receiving washer fluid from the reservoir adjusting the concentration of hydrocarbon additive within the fluid contained within the reservoir. The present system further includes a distribution system for providing washer fluid from the reservoir to an exterior surface of the vehicle. The separator reduces the concentration of hydrocarbon additive within the reservoir in the event that the ambient temperature is greater than freezing, increasing the concentration of the hydrocarbon additive in the event that the ambient temperature is lower than freezing. The separator may preferably comprise a distillation apparatus, a membrane apparatus, or solid absorption apparatus. All types of apparati are known to those skilled in the art of handling alcohol or hydrocarbon-based fluids and suggested by this disclosure.
According to another aspect of the present invention, the distribution subsystem included in the present windshield washer system may preferably comprise a pump and nozzle for spraying washer fluid upon an external surface of the building. The separator may further comprise a sensor for determining ambient temperature and a regulator for controlling the concentration of hydrocarbon additive within the washer fluid as a function of at least ambient temperature.
According to another aspect of the present invention, a method for minimizing the amount of freezing point depressant contained in a windshield washer fluid includes the steps of reducing the concentration of freezing point depressant in a washer fluid contained in the first reservoir, while increasing the concentration of freezing point depressant contained in a second reservoir, by introducing the freezing point depressant removed from the fluid contained within the first reservoir into the second reservoir. The present method also includes the steps of determining the ambient temperature in which the washer fluid is to be sprayed and mixing fluid from the first reservoir with fluid from the second reservoir at a ratio which is a function of at least ambient temperature. In other words, fluid having a relatively lower concentration of methanol or other freezing point depressant is mixed with fluid having a much higher concentration of methanol, so as to achieve a mixture which, although is freeze-resistant, will contain the minimum amount of alcohol to achieve the required freeze resistance.
It is an advantage of the present invention that use of methanol or other alcohol yet other type of hydrocarbon freezing point depressants with automotive windshield washer systems will be minimized.
It is another advantage of the present invention that cost of operating a vehicle will be reduced because the motorist will be able to use neat water as an additive fluid or an additional fluid for the vehicle under certain conditions.